1. Field of the Invention
The present invention relates to an audio processing apparatus and method.
2. Description of the Related Art
Conventionally, an audio processing apparatus, which has an ALC (Automatic Level Control) function for controlling a level of an input audio to an appropriate level, is known (see Japanese Patent Laid-Open No. 2008-129107). The ALC roughly executes control to suppress a level when an input sound is too large (limit operation) or to amplify a level when it is too small (recovery operation). In this case, a measure against a case in which a sudden sound, that is, a sound which rises abruptly and falls abruptly soon after is input becomes problematic. Such sound is generally called “attack sound”. More specifically, when a leading edge of the attack sound is input, a level is suppressed by the limit operation. After that, when a falling edge of the attack sound is input, the level is increased by the recovery operation. However, since the attack sound falls abruptly, the recovery operation reacts slowly, and an audio level immediately after the falling edge becomes too small to be harder to hear.
Hence, in the recovery operation upon detection of an attack sound, a level gain is set to be higher than usual, thus quickening a recovery reaction.
However, when attack sounds are successively input at short intervals, if the level gain is set to be higher than usual in the recovery operation of one attack sound, an audio is unwantedly clipped and distorted at a leading edge of each subsequent attack sound.